arm_fpga: Add devicetree file

The FPGA images used in Arm Ltd. focus on CPU cores, so they share a
common platform, with a minimal set of peripherals (interconnect, GIC,
UART).
This allows to support most platforms with a single devicetree file.
The topology and number of CPU cores differ, but those will added at
runtime, in BL31. Other adjustments (GICR size, SPE node, command line)
are also done at this point.

Add the common devicetree file to TF-A's build system, so it can be
build together with BL31. At runtime, the resulting .dtb file should be
uploaded to the address given with FPGA_PRELOADED_DTB_BASE at build time.

Change-Id: I3206d6131059502ec96896e95329865452c9d83e
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

fdts/arm_fpga.dts

@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: (GPL-2.0 or BSD-3-Clause)
+/*
+ * Copyright (c) 2020, Arm Limited. All rights reserved.
+ *
+ * Devicetree for the Arm Ltd. FPGA platform
+ * Number and kind of CPU cores differs from image to image, so the
+ * topology is auto-detected by BL31, and the /cpus node is created and
+ * populated accordingly at runtime.
+ */
+
+#include <dt-bindings/interrupt-controller/arm-gic.h>
+
+/dts-v1/;
+
+/ {
+	model = "ARM FPGA";
+	compatible = "arm,fpga", "arm,vexpress";
+	interrupt-parent = <&gic>;
+	#address-cells = <2>;
+	#size-cells = <2>;
+
+	aliases {
+		serial0 = &dbg_uart;
+	};
+
+	chosen {
+		stdout-path = "serial0:38400n8";
+		bootargs = "console=ttyAMA0,38400n8 earlycon";
+		/* Allow to upload a generous 100MB initrd payload. */
+		linux,initrd-start = <0x0 0x84000000>;
+		linux,initrd-end = <0x0 0x85400000>;
+	};
+
+	/* /cpus node will be added by BL31 at runtime. */
+
+	psci {
+		compatible = "arm,psci-0.2";
+		method = "smc";
+	};
+
+	timer {
+		compatible = "arm,armv8-timer";
+		clock-frequency = <10000000>;
+		interrupts = <GIC_PPI 13 IRQ_TYPE_LEVEL_LOW>,
+			     <GIC_PPI 14 IRQ_TYPE_LEVEL_LOW>,
+			     <GIC_PPI 11 IRQ_TYPE_LEVEL_LOW>,
+			     <GIC_PPI 10 IRQ_TYPE_LEVEL_LOW>;
+	};
+
+	pmu {
+		compatible = "arm,armv8-pmuv3";
+		interrupts = <GIC_PPI 7 IRQ_TYPE_LEVEL_HIGH>;
+	};
+
+	/* This node will be removed at runtime on cores without SPE. */
+	spe-pmu {
+		compatible = "arm,statistical-profiling-extension-v1";
+		interrupts = <GIC_PPI 5 IRQ_TYPE_LEVEL_HIGH>;
+	};
+
+	memory@80000000 {
+		device_type = "memory";
+		reg = <0x0 0x80000000 0x0 0x80000000>,
+		      <0x8 0x80000000 0x1 0x80000000>;
+	};
+
+
+	bus_refclk: refclk {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <100000000>;
+		clock-output-names = "apb_pclk";
+	};
+
+	uartclk: baudclock {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <10000000>;
+		clock-output-names = "uartclk";
+	};
+
+	dbg_uart: serial@7ff80000 {
+		compatible = "arm,pl011", "arm,primecell";
+		reg = <0x0 0x7ff80000 0x0 0x00001000>;
+		interrupts = <GIC_SPI 115 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&uartclk>, <&bus_refclk>;
+		clock-names = "uartclk", "apb_pclk";
+	};
+
+	gic: interrupt-controller@30000000 {
+		compatible = "arm,gic-v3";
+		#address-cells = <2>;
+		#interrupt-cells = <3>;
+		#size-cells = <2>;
+		ranges;
+		interrupt-controller;
+		reg = <0x0 0x30000000 0x0 0x00010000>,	/* GICD */
+	/* The GICR size will be adjusted at runtime to match the cores. */
+		      <0x0 0x30040000 0x0 0x00020000>;	/* GICR for one core */
+		interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH>;
+	};
+};

plat/arm/board/arm_fpga/platform.mk

@@ -81,6 +81,8 @@ FPGA_GIC_SOURCES	:=	${GICV3_SOURCES}			\
 				plat/common/plat_gicv3.c		\
 				plat/arm/board/arm_fpga/fpga_gicv3.c
 
+FDT_SOURCES		:=	fdts/arm_fpga.dts
+
 PLAT_INCLUDES		:=	-Iplat/arm/board/arm_fpga/include
 
 PLAT_BL_COMMON_SOURCES	:=	plat/arm/board/arm_fpga/${ARCH}/fpga_helpers.S